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Investigation and modelling of the electrical charging effect in birch wood above the fibre saturation point (FSP)

Valdek Tamme

Valdek Tamme

Institute of Forestry and Engineering, Estonian University of Life SciencesTartu, Estonia
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Tamme, Valdek
, 
Alar Jänes

Alar Jänes

Institute of Chemistry, University of TartuTartu, Estonia
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Jänes, Alar
, 
Tavo Romann

Tavo Romann

Institute of Chemistry, University of TartuTartu, Estonia
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Romann, Tavo
, 
Hannes Tamme

Hannes Tamme

Institute of Forestry and Engineering, Estonian University of Life SciencesTartu, Estonia
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Tamme, Hannes
, 
Peeter Muiste

Peeter Muiste

Institute of Forestry and Engineering, Estonian University of Life SciencesTartu, Estonia
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Muiste, Peeter
 and 
Ahto Kangur

Ahto Kangur

Institute of Forestry and Engineering, Estonian University of Life SciencesTartu, Estonia
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Kangur, Ahto
  
May 04, 2023
Investigation and modelling of the electrical charging effect in birch wood above the fibre saturation point (FSP)'s Cover Image
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Article Category: Research paper
Published Online: May 04, 2023
Page range: 21 - 37
Received: Dec 03, 2022
Accepted: Dec 28, 2022
DOI: https://doi.org/10.2478/fsmu-2022-0010
Keywords
© 2022 Valdek Tamme et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1.

Equivalent circuits used for modelling in the frequency domain: (a) equivalent circuit (II) adapted from the study by Zelinka et al. (2008), and (b) a simplified version of the equivalent circuit (I). Rel is electrolyte (birch sap) resistance, CPE is the constant phase element, Rct is charge transfer resistance, Cdl is double-layer electrical capacitance, and Zw is the Warburg element.
Equivalent circuits used for modelling in the frequency domain: (a) equivalent circuit (II) adapted from the study by Zelinka et al. (2008), and (b) a simplified version of the equivalent circuit (I). Rel is electrolyte (birch sap) resistance, CPE is the constant phase element, Rct is charge transfer resistance, Cdl is double-layer electrical capacitance, and Zw is the Warburg element.

Figure 2.

Schematic diagram of the measuring cell (a), and typical current curves recorded with the CCD measuring procedure in the charging and discharging process (b). DUT means “device under test” using the selected measuring procedure, L – longitudinal and T– tangential directions, e1 and e2 are symmetrical pin electrodes, E is the electrical potential with equivalent potential lines, and birch wood or birch liquid sap are the mediums studied.
Schematic diagram of the measuring cell (a), and typical current curves recorded with the CCD measuring procedure in the charging and discharging process (b). DUT means “device under test” using the selected measuring procedure, L – longitudinal and T– tangential directions, e1 and e2 are symmetrical pin electrodes, E is the electrical potential with equivalent potential lines, and birch wood or birch liquid sap are the mediums studied.

Figure 3.

Some of the values of energy which is stored in wood when compared to transmitted energy, depending upon the potential which can be applied to the electrodes (a), and (b) the dependencies of conventional CHA(E) (Schlumberger) and energetic chargeability CHA(W) on the potential applied to the electrodes.
Some of the values of energy which is stored in wood when compared to transmitted energy, depending upon the potential which can be applied to the electrodes (a), and (b) the dependencies of conventional CHA(E) (Schlumberger) and energetic chargeability CHA(W) on the potential applied to the electrodes.

Figure 4.

Different integral electrical capacitances as dependent on the electrode potential, (a) integral electrical capacitances of birch wood and birch sap in the charging process, and (b) integral electrical capacitances of birch wood and birch sap in the discharging process.
Different integral electrical capacitances as dependent on the electrode potential, (a) integral electrical capacitances of birch wood and birch sap in the charging process, and (b) integral electrical capacitances of birch wood and birch sap in the discharging process.

Figure 5.

Dependencies of energies stored in birch wood and birch sap on the transmitted primary energy (a), and (b) the energetic chargeability of birch wood and birch sap as dependent on the transmitted primary energy.
Dependencies of energies stored in birch wood and birch sap on the transmitted primary energy (a), and (b) the energetic chargeability of birch wood and birch sap as dependent on the transmitted primary energy.

Figure 6.

Ratios between secondary energies stored in wood and sap as dependent on the transmitted primary energy (a), and (b) comparison of direct current strengths of the CCD and EIS measuring procedures at different potentials (at the time moment of 240 sec.).
Ratios between secondary energies stored in wood and sap as dependent on the transmitted primary energy (a), and (b) comparison of direct current strengths of the CCD and EIS measuring procedures at different potentials (at the time moment of 240 sec.).

Figure 7.

Nyquist plots at different electrode potentials for birch wood- (a) and birch sap- (b) based systems, respectively.
Nyquist plots at different electrode potentials for birch wood- (a) and birch sap- (b) based systems, respectively.

Figure 8.

Calculation of Rct and σ from impedance data for birch wood- (a) and birch sap- (b) based systems at potential 0.8V.
Calculation of Rct and σ from impedance data for birch wood- (a) and birch sap- (b) based systems at potential 0.8V.

Figure 9.

Dependence of the mass-transfer coefficient on the electrode potential for birch wood- and birch sap-based systems.
Dependence of the mass-transfer coefficient on the electrode potential for birch wood- and birch sap-based systems.

Figure 10.

Dependence of series capacitance at frequency f = 25.5 mHz on electrode potential for birch wood- and birch sap-based systems.
Dependence of series capacitance at frequency f = 25.5 mHz on electrode potential for birch wood- and birch sap-based systems.

Figure 11.

Dependence of phase angle (a) and log -Z″ (b) on AC frequency for birch wood- and birch sap-based systems at potential 0.8 V.
Dependence of phase angle (a) and log -Z″ (b) on AC frequency for birch wood- and birch sap-based systems at potential 0.8 V.

Values of electrical parameters measured and calculated using direct current in the process of charging and discharging in wood and sap at different electrode potentials_ E – potential in volts_ W2 – primary energy_ W2 – secondary energy_ C1int – the primary integral electrical capacitance_ C2int – the secondary integral electrical capacitance_ CHA(E) – conventional chargeability and CHA(W) – energetic chargeability, according to the Formulas (1) (2) (3) (4) (6) and (7)_

Birch wood (B)
E / V W1 / mJ W2 / mJ C1,int / mF C2,int / mF CHA(E) CHA(W)
Legend on the figures W1(B) W2(B) C1(B) C2(B) CHA(E)(B) CHA(W)(B)
0.4 0.0269 0.0092 0.172 0.0605 0.975 0.34
0.8 0.124 0.0455 0.202 0.0767 0.963 0.37
1.2 0.466 0.191 0.326 0.135 0.992 0.407
1.8 2.069 0.768 0.737 0.316 0.867 0.373
2.6 7.973 2.442 1.541 0.617 0.765 0.306

The capability of various measuring procedures to determine the potential and current strength of electrodes in the studied medium in the process of electrical charging and discharging_ W1 – primary transmitted energy_ W2 – secondary stored energy_ E(t) – the time dependence of potential_ I(t) – the time dependence of current_ PDM – polarization-depolarization method_ CCD – chrono charging-discharging_ CP – chrono-potentiometry_ EIS – electrical impedance spectroscopy_ CV – cyclic voltammetry_

Measuring procedure Primary W1 – charging process Secondary W2 – discharging process
E(t) I(t) E(t) I(t)
PDM yes yes yes yes
CCD yes yes no yes
CP yes yes yes no
EIS yes yes no no
CV yes yes yes yes

Results of modelling the equivalent circuit shown in Figure 1b with the ZView ver_ 2_3 (Scribner Inc_, 2022) program in the frequency domain_

Birch wood
E / V χ 2 R el / Ω C dl / μF R ct / kΩ R D / kΩ T / s rad -1 α w
0 0.00107 283.8 9.86 14.9 89.22 4.615 0.406
0.4 0.00103 273.7 12.89 14.7 71.38 5.166 0.361
0.8 0.00114 295.3 17.397 14.84 67.10 2.544 0.403
1.2 0.0014 285.8 22.78 14.89 70.76 2.057 0.421
1.8 0.00963 285.4 13.36 13.24 134.28 5.51 0.225
2.6 0.00732 256.2 9.485 12.62 65.99 4.46 0.055

Values of electrical parameters measured and calculated using direct current in the process of charging and discharging in wood and sap at different transmitted primary energies_ W1 – primary transmitted energy in millijoules (mJ)_

Primary energy, W1 / mJ W2 / mJ, (B) W2 / mJ, (BS) CHA (W), (B) CHA(W), (BS) W2(B)/ W2(BS)
Legend W2(B) W2(BS) CHA(W)(B) CHA(W)(BS) W2(B)/ W2(BS)
7.97 2.38 0.315 0.298 0.0395 7.5
32.9 3.683 1.191 0.112 0.0362 3.092
57.89 4.146 2.067 0.0716 0.0357 2.006
107.8 4.499 3.82 0.0417 0.0354 1.178

Results of modelling the equivalent circuit shown in Figure 1a with the ZView ver_ 2_3 [35] program in the frequency domain_ χ 2 – goodness parameter of fitting_ CPE – constant phase element_ E – potential in volts_ Rel – resistance of the electrolyte (sap)_ Cdl – double layer capacitance_ Rct – the charge transfer resistance_ RD – the limiting diffusion resistance_ T – the diffusion time constant_ αw – fractional exponent for Warburg-like diffusion impedance_ α – the CPE fractional exponent_

Birch wood
E / V χ 2 R el / Ω C dl / μF R ct / kΩ R D / kΩ T / s rad-1 α w α
0 0.00433 238.8 12.13 15.5 611.6 78.29 0.52 0.936
0.4 0.00433 237.7 12.13 15.8 611.6 78.29 0.52 0.936
0.8 0.00424 295.3 20.31 15.6 74.25 2.21 0.47 0.938
1.2 0.00685 285.8 23.56 15.54 68.08 1.695 0.462 0.939
1.8 0.00432 285.4 97.65 15.54 63.19 1.21 0.461 0.939
2.6 0.00325 256.2 21.32 14.83 34.23 1.383 0.278 0.943
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